It had fallen below 50 for months, but finally perked up again in August with a final reading of 50.1. Any number over 50 indicates a faster pace of manufacturing activity.

China's factories saw "firmer footing" on the back of higher demand, which is expected to remain strong as government stimulus measures continue to boost the economy, said HSBC's China economist Hongbin Qu.

However, some economists are cautioning that the economic recovery may lose momentum after November, when the Chinese government holds a party meeting.

Nomura economist Zhiwei Zhang said monetary policy may tighten as the government moves "to shift its focus away from the speed of growth, towards efforts to rebalance the economy and improve the quality of growth."